Network card route


I have one computer (A) with 2 NIC's

I have another computer (B) with 1 NIC

CompA can see the 1.X network and 2.X fine
CompB can see CompA which is fine also

Is there a way for CompC on the 1.X range to see the 2.X network.
CompC only has one network card.

Is there a way to add a route on the NIC or something.  I know i can install another NIC for the 2.X range.  But i am wondering if there is a way for one network card to ping or communicate with both 1.X and 2.X range thru the network.  at the same time.  

Who is Participating?

There are 3 issues here:

1. Computer A needs to be capable of routing packets from one NIC to another. (this is assuming there is no other way to get from 1x to 2x)

2. Computer C needs to know which way to go to find the 2x network. Assuming the default gateway on computer C is NOT computer A, then you will need to give it the route.

3. The computers on the 2x network need to know how to get to the 1x network, so they can respond to computer C.


step 1

I'm assuming computer A is a Windows XP Pro machine. You need to enable IP Routing so that computer a will forward packet between NIC's. If it's no XP pro then google IP Routing for that OS and I'm sure you'll find a how-to.

For XP Pro:

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To enable TCP/IP forwarding, follow these steps: 1. Start Registry Editor (Regedit.exe).
2. In Registry Editor, locate the following registry key:
3. Set the following registry value:
Value Name: IPEnableRouter
Value type: REG_DWORD
Value Data: 1
A value of 1 enables TCP/IP forwarding for all network connections that are installed and used by this computer.  
4. Quit Registry Editor.

Step 2, again assuming it's windows:

From a command prompt on computer c:

route add -p mask

Step 3:
You get the idea. Let know if you need help for computer B or other computers on it's network.

If computer A is the Default Gateway for all computers then you don't need all the static routes added, just make sure A is capapble of forwarding packets.

Hope that helps.
you have to configure comp C with network of 1.X range, with default gateway pointing to 1.100 (if that is an IP of PC A)
sometimes your should also enable or allow routing to be done on PC A
rick81Author Commented:
ok if i do that though will comp C still be able to access the internet, network shares, etc
and if so it will be running everything thru compA is that right? will this affect performance?

i thought there might be some sort of script.  all i wont to do is access a network share from 2.X range from compC (1.X).  would someone know how to write a script so that when i clicked on the shortcut to compB it would use compA gateway.  and when not in use it would use the normal routing.

On-Demand: Securing Your Wi-Fi for Summer Travel

Traveling this summer?Check out our on-demand webinar to learn about the importance of Wi-Fi security and 3 easy measures you can start taking immediately to protect your private data while using public Wi-Fi. Follow us today to learn more!

don't know about the script, but if your pc C already has it's primary ip address with default gateway set to access internet and you want it to go to network 1.x via pc A, then you should do on pc C:
route add mask

if you want to have this route even after pc reboots use -p flag
route -p add mask
rick81Author Commented:
below are the actual ip's.  (A) has two NIC cards

A -
B -
C -

I want to access B from C.
tried the route
route add mask
gave a mask error?  any ideas
route add mask shoud work

please also provide me with ipconfig output on all 3 pcs
rick81Author Commented:

PCB (not sure on g/way)  this is a linux box

the route added successfully and i can ping 2.100 (B) but not 2.50(C)
rick81Author Commented:
as PC A is connected to the 1.X network it pings its other 2.X address.  With or without the route from PC C
you don't need to add any routes to PC A
on pc B you shoud execute also route command with route to PC C:
route add mask
rick81Author Commented:
yeh i didnt add a route to PC A

i cannot add a route to PC B as it is a linux box.  I have no idea here.
looks like im stuck on this one.
on linux you should type:
route add -net netmask gw

don't give up there ;)
to get information of ips configured on interface in linux:
netstat -in
to get routes:
netstat -rn
rick81Author Commented:
thanks.  i dont have access to the linux box as yet.
will get back to you.  thanks so far.

rick81Author Commented:
if i had another NIC in the linux box (B)
and had it set as 192.168.1.XX

then any pc on the 1.XX network could access it.  aswell as (A) and (B) on the 2.X range.

is that correct?
yepp, correct, but you should also consider correct routing:
every host should have route to particular subnet, otherwise packets will be sent to default route.
so when you add new subnet behind any new PC our router, all PCs should understand where to sent packets for that new subnet. Thats why you use route add command
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.